Study to Evaluate the Safety of Novartis MenACWY Conjugate Vaccine When Administered With Routine Infant Vaccinations to Healthy Infants: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study to Evaluate the Safety of Novartis MenACWY Conjugate Vaccine When Administered With Routine Infant Vaccinations to Healthy Infants (NCT00806195), a randomized phase 3 study. The primary outcome is Percentages of Subjects With At Least One Severe Systemic Reaction After Any Vaccination.

2. Clinical Question

This is a safety and tolerability question about reactions recorded after vaccination, rather than a comparison of protection against meningococcal infection. The main contrast asks whether adding MenACWY-CRM197 alongside routine infant vaccinations is associated with a different observed percentage of subjects reporting a severe systemic reaction than routine vaccines alone. The registry describes the comparison as non-inferiority or equivalence, but the margin needed to judge that question is not reported in the registry record. The results therefore need to be read as a reported contrast with its uncertainty, not as a conclusive demonstration of equivalence or non-inferiority.

3. Trial Design

The registry identifies this as a phase 3b, randomized, parallel-group, multicenter, open-label study. It is listed as completed, with enrollment of 7744. The primary objective was to evaluate the safety and tolerability of Novartis MenACWY conjugate vaccine when administered with routine infant vaccinations to healthy infants. The registry lists meningitis and meningococcal infection as conditions, but the primary outcome is a safety measure.

The primary comparison is between the MenACWY-CRM197 plus routine vaccines detailed group and the routine vaccines detailed group. The endpoint analysis lists 1349 subjects in the combined-vaccination group and 461 in the routine-vaccines group. These are the analysis-group sizes reported for this outcome, not the total enrollment. The registry describes the primary population as an as-treated safety population: subjects had received at least one study dose and provided postbaseline safety data, and were assigned analytically to the group corresponding to the vaccination actually received.

The intervention schedule included MenACWY-CRM197 at 2, 4, 6 and 12 months of age, with routine vaccines given according to local schedules. The routine vaccine list includes DTaP, Hib, IPV, pneumococcal conjugate, MMR, varicella and hepatitis A. The registry’s arm descriptions distinguish detailed and other group labels; the primary endpoint specifically compares the detailed groups. The registry record does not report enough complete detail to reconstruct every participant’s exact vaccine schedule from the truncated arm descriptions.

Open-label means the study was not masked. Knowledge of assigned vaccination could potentially influence how symptoms are noticed, reported, or assessed, although the registry does not state whether any such influence occurred. Randomization supports a planned group comparison, but the analysis is as treated rather than simply defined by original assignment. The methods used to generate the allocation sequence, conceal assignments, or address departures from assigned treatment are not reported in the registry record.

The registry describes the study as randomized and parallel-group, but does not report the randomization ratio or the rationale for the analyzed group sizes. It also does not report the protocol’s sample-size justification, interim analyses, or a detailed statistical analysis plan. Those omissions limit reconstruction of how the study was designed to support a formal non-inferiority or equivalence conclusion.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: All subjects enrolled were included in the trial.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Analysis was done on As Treated Safety Population - Subjects who received at least one study dose and provided postbaseline safety data, and that subjects would be included in the group for the vaccination actually received (i.e., analyzed as treated).

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Percentages of Subjects With At Least One Severe Systemic Reaction After Any Vaccination, measured over 15 minutes to Day 7 after any vaccination administered at 2, 4, 6 and 12 months of age.

The primary endpoint is the percentage of subjects with at least one severe systemic reaction after any vaccination. The assessment window began 15 minutes after vaccination and continued to Day 7. It covered vaccinations administered at 2, 4, 6 and 12 months of age. The endpoint therefore summarizes whether a subject experienced a qualifying reaction during the stated post-vaccination period; it is not a count of every reaction episode or a measure of reaction duration.

This type of endpoint is used to compare the frequency of a safety event across vaccination groups. A subject-level percentage can provide a direct view of how common the recorded event was in each analyzed group, while avoiding the impression that repeated reactions in the same subject are independent observations. The registry labels the outcome as percentages of subjects, although the arm values are displayed as 16.0 and 13.0 and the reported difference as 3.0.

The term “severe systemic reaction” is important to interpretation, but the registry record does not report the criteria used to classify a reaction as severe or systemic. It describes the detailed groups as including reactogenicity and all adverse events for 7 days, serious adverse events, and medically attended adverse events. The primary endpoint’s exact event definitions, symptom list, and rules for handling overlapping reactions are not reported in the registry record.

The endpoint is suited to a safety comparison over a specified post-vaccination period. It does not, by itself, establish the cause of a reaction, describe its clinical course, or answer whether the vaccines prevent disease. Its meaning depends on consistent event ascertainment across groups, which is especially relevant in an open-label study.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The posted primary analysis uses the Miettinen and Nurminen method and reports a mean difference for final values. In this setting, the measured outcome is a percentage of subjects, so the reported contrast describes the difference between group percentages on the outcome scale. The registry gives the estimate as 3.0 and the 95% confidence interval as -0.8 to 6.4. These are the sponsor’s reported analysis results; the registry does not give a p-value for the comparison.

What the confidence interval says

A confidence interval is a measure of statistical uncertainty around an estimate. It reflects how much the estimated contrast could vary across repeated studies conducted under comparable conditions and analyzed with the same method. It does not mean that a particular percentage of individual subjects falls within the interval, and it does not account automatically for every source of bias or uncertainty.

For this outcome, the interval runs from -0.8 to 6.4 and includes the null contrast. That means the reported interval is compatible with values on either side of no difference. Its width also shows that the estimate is not an exact measure of the underlying contrast. Interpretation should take account of the clinical and statistical decision rule, not simply whether the interval includes the null.

Why non-inferiority needs a margin

In a non-inferiority analysis, the question is whether the result rules out an unacceptable amount of loss on the specified outcome scale. A margin defines what amount is considered acceptable for the purpose of the comparison. Equivalence is a related but distinct question: it generally asks whether the uncertainty is sufficiently contained within prespecified limits in both directions. These conclusions rely on the margin, the direction of the comparison, and the analysis rules being specified in advance.

The registry labels the reported analysis as non-inferiority or equivalence, but the margin and decision criteria are not reported in the registry record. As a result, the confidence interval cannot be judged against the intended threshold from the registry information. A confidence interval that includes the null does not, by itself, establish equivalence; a positive point estimate does not, by itself, establish non-inferiority.

How the endpoint is summarized

The outcome is defined at the subject level: whether a subject reported at least one severe systemic reaction during the stated post-vaccination period. This differs from an event-count outcome, where multiple episodes from one subject may contribute separately. A subject-level percentage can make the group contrast easier to interpret as the frequency of affected subjects, but the meaning still depends on event definitions, ascertainment, and the completeness of safety reporting.

The reported analysis concerns final values and a difference between groups. The registry does not report a detailed model specification, adjustment variables, or the exact approach used for missing outcome observations. It also does not report the formal assumptions used for the Miettinen and Nurminen calculation beyond naming the method. Those details matter for a full independent audit of the analysis.

Over-dispersion and count outcomes

General statistical context: for count outcomes, over-dispersion means that observed variability exceeds what a simple model would expect. If it is ignored, standard errors and confidence intervals can be too small, making uncertainty appear less than it is. This concept is not a reported feature of this primary outcome: the primary endpoint is a percentage of subjects with at least one reaction, not a count of recurrent events. The registry’s separate adverse-event summaries include counts of affected subjects and event terms, but no over-dispersion model is reported.

Analysis population and treatment assignment

The primary population is described as as treated. Subjects who received at least one study dose and provided postbaseline safety data were included according to the vaccination actually received. This definition focuses the analysis on treatment exposure as received, but it may differ from an analysis that retains subjects in their randomized groups regardless of what they received. The registry does not report a parallel intention-to-treat analysis or explain whether both approaches were prespecified. In non-inferiority settings, analysis-population choices can be particularly important, so the absence of those details limits assessment.

Randomization is listed as the allocation method, but the registry does not report sequence generation, allocation concealment, or the handling of protocol deviations. Open-label conduct also means group assignment was not masked. For a reported symptom-based endpoint, awareness of treatment could influence reporting or assessment; the available registry information does not quantify whether this affected the results.

Multiplicity and missing information

The registry lists three secondary outcomes in addition to the primary endpoint and reports four outcome measures overall. It does not report a multiplicity adjustment or a hierarchy for interpreting multiple outcomes. When several hypotheses are assessed, the chance of at least one apparently notable result can increase unless the analysis plan accounts for the number and relationship of tests. No adjustment should be assumed where none is described.

The registry record also does not report the number of subjects with missing primary endpoint data, imputation rules, or sensitivity analyses for missingness. It does not report interim analyses or the protocol’s sample-size justification. These absences prevent a complete assessment of whether the planned analysis, event ascertainment, and handling of incomplete data support the intended inference.

10. Analyses Reported by the Sponsor

The registry reports the sponsor’s primary analysis as a Miettinen and Nurminen comparison, with a mean difference of 3.0 and a 95% confidence interval from -0.8 to 6.4. The analysis is classified as non-inferiority or equivalence. The registry does not include a p-value, the decision margin, or enough information to reconstruct the formal decision rule.

No recalculated result is available for this endpoint in the posted results. Consequently, there is no separate recalculation to compare with the sponsor’s estimate, and no basis to characterize a discrepancy between them. The reported sponsor analysis is therefore the result to interpret. The point estimate and interval should be read in light of the missing non-inferiority or equivalence margin rather than as a stand-alone demonstration of either conclusion.

A recalculation from summary statistics, when available, would generally be an unadjusted check and could differ from a sponsor analysis that uses a specified method or analysis population. Such a check would not replace a prespecified trial analysis. In this case, the registry record provides the named method and reported estimate, but not the margin, detailed implementation, or full statistical analysis plan needed to independently reproduce the decision.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists three secondary outcomes: subjects with at least one serious adverse event during the study, subjects reporting solicited adverse events after each vaccination, and subjects reporting unsolicited adverse events after any vaccination. It also lists four outcome measures overall. The registry does not report whether the primary and secondary outcomes were tested within a prespecified hierarchy, whether a multiplicity adjustment was applied, or how any adjustment would affect interpretation.

Multiplicity is a general concern when multiple outcomes or comparisons are examined. The more statistical questions asked, the greater the opportunity for chance findings unless the analysis plan controls the overall error rate or defines which results are confirmatory. This does not mean that any particular reported outcome is false; it means readers need the analysis plan to distinguish confirmatory conclusions from exploratory findings. No particular adjustment should be presumed from the registry entry.

Missing-data methods are also not reported for the primary endpoint. The registry does not state how many subjects lacked postbaseline safety data or endpoint information, whether missing observations were excluded, or whether imputation or sensitivity analyses were used. Because the primary population requires postbaseline safety data, completeness and reasons for missing data could affect who contributes to the analysis. The registry provides no detail to assess that possibility.

The analysis population is described as as treated, with subjects assigned to the group for the vaccination actually received after receiving at least one study dose and providing postbaseline safety data. The registry does not report a randomized-group analysis, a per-protocol analysis, or a comparison of conclusions across analysis populations. For a non-inferiority or equivalence question, the choice of population can influence interpretation, but the available record does not permit assessment of that influence.

The registry does not report the protocol’s sample-size justification, interim analyses, allocation concealment, or a detailed statistical analysis plan. These details are relevant to judging how the study was designed to detect or rule out a prespecified difference, and whether the reported analysis matches the plan. Their absence should be treated as an information limitation, not evidence that a particular method was or was not used.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: bronchiolitis (1.1%), pneumonia (0.5%), urinary tract infection (0.5%), dehydration (0.5%), gastroenteritis (0.4%).

The registry reports serious adverse event summaries for the “All” groups, separate from the detailed groups used for the primary endpoint. In the MenACWY-CRM197 plus routine vaccines group, 354 subjects are listed as affected among 5760 at risk. In the routine vaccines group, 114 are listed as affected among 1968 at risk. These are reported counts and group totals; no new percentages are calculated from them.

The registry also lists selected serious adverse event terms with percentages: bronchiolitis, 1.1%; pneumonia, 0.5%; urinary tract infection, 0.5%; dehydration, 0.5%; gastroenteritis, 0.4%; and respiratory syncytial virus bronchiolitis, 0.4%. The registry excerpt does not specify the group-specific denominators or provide a full event-term listing alongside these percentages, so they should not be treated as a complete account of all serious adverse events.

Serious adverse events are distinct from the primary endpoint of severe systemic reactions during a defined post-vaccination window. The broader serious-event summaries concern the entire study period and use the “All” group labels, while the primary comparison concerns detailed groups and a specific reaction window. The populations and outcome definitions should not be conflated.

Deaths are not reported in the registry record. These safety figures describe reported events in the study; they do not establish causation or provide a complete account of all possible harms.

13. What the Result Does, and Does Not, Mean

The primary result is an estimated difference between the percentages of subjects with at least one severe systemic reaction after vaccination. The registry reports values of 16.0 and 13.0 for the two detailed groups, a mean difference of 3.0, and a 95% confidence interval from -0.8 to 6.4. This is a summary of the observed safety endpoint in the analyzed population and defined follow-up window.

The interval includes the null contrast and extends in both directions. It therefore does not pin down the direction of the underlying difference. The result should not be translated into a claim that the groups are the same, nor into a claim that one group is definitively worse. The registry’s non-inferiority or equivalence label is not enough to make that determination because the relevant margin and decision rule are not reported in the registry record.

The finding is about recorded severe systemic reactions after vaccination, not about vaccine effectiveness against meningitis or meningococcal infection. It does not establish that any event was caused by a particular vaccine. It also does not answer every safety question: serious adverse events and other adverse events are separate outcomes, with broader “All” groups and different follow-up descriptions.

General interpretation: statistical uncertainty and clinical importance are related but distinct. A confidence interval describes uncertainty in an estimated contrast; deciding whether the values it contains matter clinically requires a prespecified threshold and relevant clinical context. Neither a threshold for the primary endpoint nor the trial’s full decision criteria are reported in the registry record.

The trial concerns healthy infants and a particular schedule of MenACWY-CRM197 with routine infant vaccinations. Results from this study do not automatically apply to other populations, products, schedules, or settings. The open-label design, as-treated analysis, and missing details on event definitions and missing-data handling also qualify interpretation. The responsible conclusion is limited to the reported estimate, interval, study population, and outcome definition.

14. Why This Trial Matters Statistically

This trial illustrates why the label attached to a statistical analysis cannot substitute for the information needed to interpret it. A non-inferiority or equivalence comparison depends on a specified margin and a decision rule. The registry reports the estimate and confidence interval but not those criteria. Readers can describe the numerical contrast and its uncertainty, but cannot verify from the registry record whether the formal claim was satisfied.

It also demonstrates the importance of distinguishing endpoint-specific analysis groups from overall enrollment and broader safety groups. The primary analysis lists 1349 and 461 subjects in the detailed groups, while the serious-event summaries use “All” groups with 5760 and 1968 subjects at risk. These figures relate to different summaries and should not be substituted for one another.

The endpoint is binary at the subject level: a person either reported at least one qualifying reaction during the stated period or did not. This is conceptually different from counting every event or describing severity over time. Such distinctions affect what a percentage estimates and what conclusions it can support.

Finally, the open-label design, as-treated population, and unreported details on missing data and multiplicity show why results need more than an estimate and interval for full appraisal. The record gives a useful account of the primary contrast, but several details needed to assess the planned inference are not reported. Making those limits explicit is part of sound statistical interpretation, especially when the stated objective concerns a formal safety comparison.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The primary endpoint’s reported values are percentages of subjects, but the registry does not provide the operational criteria for “severe” or “systemic,” the symptom list, or the rules for counting reactions occurring after more than one vaccination. That limits independent evaluation of event classification and consistency across participants.

The study was open-label, and masking is listed as none. For symptoms that depend partly on reporting or assessment, knowledge of vaccination assignment could affect ascertainment. The registry does not report whether event assessors were independent or whether procedures were used to reduce reporting differences.

The primary population is as treated, not described as an analysis by randomized assignment. The registry does not report an intention-to-treat comparison, a per-protocol analysis, or sensitivity analyses across populations. It also does not provide the number of missing endpoint observations or how missing data were handled. These details limit assessment of potential selection and analysis effects.

Although the analysis is classified as non-inferiority or equivalence, the margin and detailed decision rule are not reported in the registry record. The protocol’s sample-size justification and any interim analyses are also not reported. Without these items, the planned operating characteristics and formal conclusion cannot be independently checked.

The intervention arm descriptions are partly truncated, and routine vaccines were administered according to local schedules. The registry therefore does not provide a complete participant-level account of the exact coadministration schedules. The primary comparison is limited to the detailed groups; safety summaries for the “All” groups refer to different populations. These distinctions, together with the absence of a full statistical analysis plan and multiplicity procedures, constrain how broadly or definitively the results can be interpreted.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Study to Evaluate the Safety of Novartis MenACWY Conjugate Vaccine When Administered With Routine Infant Vaccinations to Healthy Infants — NCT00806195.
• Registry record last updated 2013-07-09; status last verified 2013-05.
• Results first posted 2013-07-09.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT00806195 is a completed, randomized, open-label, parallel-group, multicenter phase 3b study in healthy infants, with enrollment of 7744. Its primary objective was to evaluate the safety and tolerability of MenACWY-CRM197 given with routine infant vaccinations.

The primary endpoint was the percentage of subjects with at least one severe systemic reaction from 15 minutes to Day 7 after vaccinations at 2, 4, 6 and 12 months of age. In the detailed groups, the registry reports 16.0 for MenACWY-CRM197 plus routine vaccines and 13.0 for routine vaccines alone. The reported difference is 3.0, with a 95% confidence interval from -0.8 to 6.4, using the Miettinen and Nurminen method.

The result is labeled as a non-inferiority or equivalence analysis, but the margin and decision rule are not reported in the registry record. Broader serious adverse event summaries are reported separately for “All” groups. The record does not report sufficient detail on missing data, multiplicity, or the full statistical analysis plan to independently reconstruct the intended formal conclusion.